Vialinin B (1) is a highly oxygenated dibenzofuran bearing p-hydroxyphenyl and phenylacetoxy groups that was isolate by us from the dry fruiting bodies of an edible Chinese mushroom, Thelephora vialis, and shows an extremely potent inhibitory activity against tumor necrosis factor (TNF)-α production in rat basophilic leukemia (RBL-2H3) cells (IC_<50>=20pM vs 0.25nM for FK-506).TNF-α is a potent multifunctional cytokene that mediates a variety of biological actions with a central fole in the pathogenesis of many inflammatory diseases. Thus, inhibitors of TNF-α production in the activated mast cells and basophils are promising candidates for a new type of anti-allergic agent. In ghis symposium, we present total synthesis of 1 and its related compuonds. The key reactions include a double Suzuki coupling of electron-rich aryl bromide with a couple of phenylboronic acids, a copper-mediated Ullmann reaction, an oxidative cleavage of methylene acetal, and a LHMDS-promoted phenylacetylation. This synthesis proceeded in 11 steps with 18% overall yield from a known sesamol derivative. Furthermore synthesis of the related natural products such as ganbajunin B and vialinin C is also discussed.
